Are you using an Apple Silicon (M1, M2, etc.) machine?
While TotalFinder is compatible with Apple Silicon, this is not officially supported by BinaryAge.
As a result, Apple Silicon support in TotalFinder must be manually enabled. You can find more info on how to do so on this page.
Here you can find the latest versions of TotalFinder that are compatible with each version of macOS or OS X.
Latest version (※ SIP must remain weakened)
TotalFinder 1.12.3 (※ SIP must remain weakened)
TotalFinder 1.12.3 (※ SIP must be temporarily disabled)